This invention relates to novel heterocyclicguanidines which are antagonists at the serotonin 5HT.sub.3 receptor and useful as anti-emetic agents in warm blooded animals, particularly the emesis caused by administration of the anticancer drug cisplatin. In addition, the compounds of the present invention are useful in the treatment of schizophrenia, anxiety, pain and gastrointestinal disorders.
Compounds recognized for their ability to act as antagonists at the serotonin 5HT.sub.3 receptor sites are described in U.S. Pat. Nos. 4,593,034 and 4,749,718 and U.K. patent application Nos. 2,125,398A, 2,166,726A, 2,166,727A, 2,166,728A and 2,193,633A.